Impedance type distance relay



1947- w. K. SONNEMANN 2,425,759

IMPEDANCE TYPE DISTANCE RELAY Filed March 15, 1945 \a/mv fesl sfance INVENTOR M/flam/(Sonnemann,

WlTNESSES:

ATTORNEY Patented Aug. 19, 1947 IMPEDANCE TYPE DISTANCE RELAY William K. Sonnemann, Roselle Park, N. J., as-

signor to Westinghouse Electric East Pittsburgh, vania Corporation,

Pa., a corporation of Pennsyl- Application March 15, 1945, Serial No. 582,884

Claims.

' adjustable distance-type relay which has advantages in its adaptability for the adjustment of the relay-characteristic, so that its response-circle may be caused to be placed in different predetermined positions on rectangular coordinates of line-resistance and line-reactance.

An object of the invention is to provide a differential relay, having an operating-coil fluxproducing means, and a restraint-coil flux-producing means, with exciting-circuit means for exciting one of the flux-producing means in response to line-voltage alone, and with excitingcircuit means for exciting the other flux-producing means in response to both the line-voltage and the line-current, and with means for varying the ratio of the two voltage-responsive force-components to predetermined values greater or less than unity, and with means for varying the magnitude and the phase-angle of the currentrespouse, or for separately varying the in-phase and out-of-phase components of the current-response, or the like.

With the foregoing and other objects in view, my invention consists in the combinations, systems, methods, apparatus, and parts hereinafter described and claimed, and illustrated in the accompanying drawing, wherein Figure 1 is a diagrammatic view of circuits and apparatus illustrating my invention in a preferred form of embodiment,

Fig. 2 is a circle-diagram which is referred to in the derivation of the formulas, and

Fig. 3 is a circle-diagram which is referred to in an illustration of the method of adjustment of the relay.

In Figure 1, I have illustrated my invention as applied to a differential relay 4 of a type having a balanced beam 5 which is acted upon by a single voltage-type operating-coil 6, and two out-ofphase voltage-type restraint-coils I and 8, in which the flux in coil 8 leads that in coil 1 by approximately 90, through the medium of a serially connected capacitor C1, so as to produce a substantially non-pulsatory restraint-force, as is well known. The front end, or operating-coil end, of the beam 5 carries a make-contact H, which closes when the relay responds, and. which is utilized to control any desired relaying-circuit l2.

The ratio K, between the effective number of turns of the restraint-coils 1 and 8, and the effective number of turns of the operating coil 6, is controlled by any suitable means, preferably by means of tap-means K on the operating coil 6,

because there is only one coil on the operating end of the beam.

According to my-present invention, the relay 4 is utilized to protect an alternating-current line I4 by detecting predetermined fault-conditions therein. The line-voltage E, or an equivalent line-derived relaying-voltage, is applied to the relay by means of a potential-transformer IS. The line'current l, or a line-derived relayingcurrent, is applied to the relay by means of a, linecurrent transformer I6, and a compensator-impedance comprising a mutual reactance or airgap transformer 7M and a resistance Re, the resistance being shunted by a variable-ratio transformer H. The primary winding of the variableratio transformer I1 is provided, with taps K, which are adjustable so as to vary the turn-ratio in magnitude and in sign or current-direction. The primary winding of the mutual reactance is provided with similar taps K2. Thus, the relay has three taps K, K1, and K2, all of which may be suitably marked or calibrated.

The line-current l is supplied to the primary windings having the taps K1 and K2.

The portion of the actuating coil 6 which is tapped by the coil-tap K is connected in series with the compensator impedances Re and 7M, and is energized across the secondary winding of the potential transformer l5.

The restraint-winding 1, and the dephased restraint-winding 8 with its serially connected capacitor C1, are both energized across the secondary winding of the potential transformer i5.

The voltage impressed on the restraining coils 1 and 8 is E, and the restraining force may be taken as E The voltage impressed on the operating coil 6 is ratios being scalar values, but variable, through zero, to either plus or minus values.

For convenience in calculation, let us use an equivalent compensator-impedance Z0 and an equivalent compensator-angle 0c as defined by the equations Substituting i=1; (6) and (KiRe-i-yKzM) Z0 4 0c in Equation 1, we may Write the operatingcoil voltage as E-IZcA (0.0-0) (5) The operating force may be taken as the square of the operating-coil turns, K times the square Dividing through by F, and remembering that E/i is the line-impedance Z, inequality (7) may be rewritten as From the response-circle diagram of Fig. applying the cosine'iormula to the triangle represented by the iii --impedance along the centerangle So, We find that At the balanem point of the relay, t itysign in line (8) an s n, and if K is not equal to l, the equation. may be rewritten, for the balance-noint,

. 2" 2 2 COS 6- =0 (10 Equating equal powers of Z in equations 9 and I0,

Equations 11, 12 l4; the circlecenterline angle So, the centermisplacement Z0,

the circle-radius Q0, in terms of the relayvariable K, K1 and It is more convenient, however, to start out with the desired circle-constants So, Z0 and Q2), and to calculate the relay-constants. Thus, the equivalent compensator-impedance found, from Equation 13, to be Substituting, in Equation 2, 30:00 from equation 11, we find that To determine which way the relay responds, whether to impedance-values Z falling inside or outside of the balance-point circle, it is necessary to restore the inequality-sign to Equation 10, and

to note that Equation 10 was derived from in equality 8 by dividing through by is positive, the division does not reverse the inequality-sign, and the relay responds when the line-impedance terminates outside of the response-circle representing the balance-point conditions. The quantity is positive when X is greater than 1, and Equation 17 shows that this is so when the circle-center displacement Z0 is greater than the circle-radius Q30 or when the origin 0 of the R, and X coordinates falls outside of the circle. If it is desired to have the tripping area (or the relay response) inside of the circle, instead of outside, it is necessary to put the inake-contacts ii at the opposite end of the beam 5 of the relay, or to replace the makecontacts H with back-oontaots 21, so that the operating and restraining coils are interchanged.

If the divisor negative, in deriving the balance-point Equation 1o from inequality (8), the inequalitysign is reversed, showing that the relay responds when the linedmpedance vector 2 terminates inside of the balance-point circle. This divisor is negative when is less than unity, and Equation 17 slot 78 that this condition prevails when the centei oii set Z0 less than the radius Q0, or, in other words, when the characteristic circle of the relay encloses the origin. Thus, a relay having a make-contact l I at the same end of the beam 5 as the operating-coil 6, as shown in Fig. 1, will have a response-area inside of the circle, as is desirable.

My present relay is not applicable to the object in View, when the response-circle is to pass through the origin, because, when the ratio h Zn/Qu becomes equal to unity the Z term vanishes, in Equation 8, and the relay no longer has a circle-response. However, the circle may be made to approach quite close to the origin.

Thus, I have provided a relay which can be adjusted to have any response-circle in which the ratio K=Zo/Qo is not too near unity. The turnratio K, of the restraint-coil turns with respect .to the operating-coil turns, deter-mines, and is determined by, the ratio of the circle-center displacement Z0 and the circle-radius Q0, as set forth by Equation 17. The absolute value of the equivalent compensator-impedance Z0, or the magnitude of the current-response 1Z0, may be adjusted to the value (Zo --Qo /Z0, as set forth by Equation 15; and the compensator-angle 60, or the phase-shift of the current-response 12s with respect to the voltage-response E at unity powerfactor, is made equal to the center-line angle So, as set forth in Equation 11. Alternatively, the in--phase and out-of-phase components of the current-response may be independently adjusted by varying the transformer-ratios K1 and K2 of If this quantity S0:71.5=center-1ine angle Z =4.04 ohms center-displacement Q0=5 ohms=circle-radius Let it be assumed that the relay-constants are M=300 ohms Re=300 ohms Then Equations 17, 18 and 19 show that the necessary relay-adjustments are The minus sign for K1 means that the taps K1 must be adjusted so that the current-direction is the reverse of that shown in Fig. 1, from which the equations were derived.

While I have shown my relay in but a single preferred form of embodiment, I wish it to be understood that the invention is susceptibl of embodiment in other forms, and I desire that the appended claims may be accorded the broadest interpretation consistent with their language.

I claim as my invention:

1. An adjustable distance-type relay compris ing a difierential relay, having an operating-coil flux-producing means, a restraint-coil flux-producing means, exciting-circuit means for exciting one of the flux-producing means in response to line-Voltage alone, exciting-circuit means for exciting the other flux-producing means in response to both the line-voltag and the line-current, means for varying the ratio of the two Voltage-responsive force-components, and means for Varying the magnitude and the phase-angle of the current-response,

2. An adjustable distance-type relay comprising a difierential relay, having an operating-coil flux-producing means, a restraint-coil flux-producing means, exciting-circuit means for exciting one of the flux-producing mean in response to line-voltage alone, excitingmircuit means for exciting the other flux-producing means in response to both the line-voltage and the line-current, means for varying the effective ampereturn ratio of the two flux-producing means, and means for varying the magnitude and the phaseangle of the current-response.

3. An adjustable distance-type relay comprising a diiterential relay, having an operating-coil flux-producing means, a restraint-coil flux-producing means, exciting-circuit means for excit ing one of the flux-producin means in response to line-voltage alone, exciting-circuit means for exciting the other flux-producing means in response to both the line-voltage and the 1ine-current, means for varying the ratio of the two voltage-responsive force-components, and, means for separately, varying the in-phase and o-ut-of-phase components of the current-response.

An adjustable distance-type relay comprising a differential relay, having an operating-coil flux-producing means, a restraint-coil flux-producing means, exciting-circuit means for exciting one of the flux-producing means in response to line-voltage alone, exciting-circuit means for exciting the other flux-producing means in response to both the line-voltage and the line-current, means for varying the effective ampere-turn ratio of the two flux-producing means, and means for separately varying the in-phase and out-of-phase components of the current-response.

5. A protective relay for use on an alternatingcurrent line, said relay comprising, in combination, a differential relay, having an operatingcoil flux-producing means, a restraint-coil fluxproducing means, voltage-responsive excitingcircuit means for exciting one of the flux-producing means in response to line-voltage alone, current-compensated voltage-responsive exciting-circuit means, including, a variable mutual compensator-reactance, for exciting the other flux-producing means in response to both the line-voltage and the line-current, and means for varying th ratio of the effective ampere-turns of the two fiux-producing means.

WILLIAM K. SONNEMANN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,276,888 Sonnemann Mar. 17, 1942 2,315,469 Warrington Mar, 30, 1943 

